/*
 * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xpath.internal;

import javax.xml.transform.TransformerException;

import com.sun.org.apache.xml.internal.utils.PrefixResolver;
import com.sun.org.apache.xml.internal.utils.PrefixResolverDefault;
import com.sun.org.apache.xpath.internal.objects.XObject;
import jdk.xml.internal.JdkXmlUtils;

import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.traversal.NodeIterator;

/**
 * The methods in this class are convenience methods into the
 * low-level XPath API.
 * These functions tend to be a little slow, since a number of objects must be
 * created for each evaluation.  A faster way is to precompile the
 * XPaths using the low-level API, and then just use the XPaths
 * over and over.
 * <p>
 * NOTE: In particular, each call to this method will create a new
 * XPathContext, a new DTMManager... and thus a new DTM. That's very
 * safe, since it guarantees that you're always processing against a
 * fully up-to-date view of your document. But it's also portentially
 * very expensive, since you're rebuilding the DTM every time. You should
 * consider using an instance of CachedXPathAPI rather than these static
 * methods.
 *
 * @see <a href="http://www.w3.org/TR/xpath">XPath Specification</a>
 */
public class XPathAPI {

    /**
     * Use an XPath string to select a single node. XPath namespace
     * prefixes are resolved from the context node, which may not
     * be what you want (see the next method).
     *
     * @param contextNode The node to start searching from.
     * @param str         A valid XPath string.
     * @return The first node found that matches the XPath, or null.
     * @throws TransformerException
     */
    public static Node selectSingleNode(Node contextNode, String str)
            throws TransformerException {
        return selectSingleNode(contextNode, str, contextNode);
    }

    /**
     * Use an XPath string to select a single node.
     * XPath namespace prefixes are resolved from the namespaceNode.
     *
     * @param contextNode   The node to start searching from.
     * @param str           A valid XPath string.
     * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
     * @return The first node found that matches the XPath, or null.
     * @throws TransformerException
     */
    public static Node selectSingleNode(
            Node contextNode, String str, Node namespaceNode)
            throws TransformerException {

        // Have the XObject return its result as a NodeSetDTM.
        NodeIterator nl = selectNodeIterator(contextNode, str, namespaceNode);

        // Return the first node, or null
        return nl.nextNode();
    }

    /**
     * Use an XPath string to select a nodelist.
     * XPath namespace prefixes are resolved from the contextNode.
     *
     * @param contextNode The node to start searching from.
     * @param str         A valid XPath string.
     * @return A NodeIterator, should never be null.
     * @throws TransformerException
     */
    public static NodeIterator selectNodeIterator(Node contextNode, String str)
            throws TransformerException {
        return selectNodeIterator(contextNode, str, contextNode);
    }

    /**
     * Use an XPath string to select a nodelist.
     * XPath namespace prefixes are resolved from the namespaceNode.
     *
     * @param contextNode   The node to start searching from.
     * @param str           A valid XPath string.
     * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
     * @return A NodeIterator, should never be null.
     * @throws TransformerException
     */
    public static NodeIterator selectNodeIterator(
            Node contextNode, String str, Node namespaceNode)
            throws TransformerException {

        // Execute the XPath, and have it return the result
        XObject list = eval(contextNode, str, namespaceNode);

        // Have the XObject return its result as a NodeSetDTM.
        return list.nodeset();
    }

    /**
     * Use an XPath string to select a nodelist.
     * XPath namespace prefixes are resolved from the contextNode.
     *
     * @param contextNode The node to start searching from.
     * @param str         A valid XPath string.
     * @return A NodeIterator, should never be null.
     * @throws TransformerException
     */
    public static NodeList selectNodeList(Node contextNode, String str)
            throws TransformerException {
        return selectNodeList(contextNode, str, contextNode);
    }

    /**
     * Use an XPath string to select a nodelist.
     * XPath namespace prefixes are resolved from the namespaceNode.
     *
     * @param contextNode   The node to start searching from.
     * @param str           A valid XPath string.
     * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
     * @return A NodeIterator, should never be null.
     * @throws TransformerException
     */
    public static NodeList selectNodeList(
            Node contextNode, String str, Node namespaceNode)
            throws TransformerException {

        // Execute the XPath, and have it return the result
        XObject list = eval(contextNode, str, namespaceNode);

        // Return a NodeList.
        return list.nodelist();
    }

    /**
     * Evaluate XPath string to an XObject.  Using this method,
     * XPath namespace prefixes will be resolved from the namespaceNode.
     *
     * @param contextNode The node to start searching from.
     * @param str         A valid XPath string.
     * @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
     * @throws TransformerException
     * @see com.sun.org.apache.xpath.internal.objects.XObject
     * @see com.sun.org.apache.xpath.internal.objects.XNull
     * @see com.sun.org.apache.xpath.internal.objects.XBoolean
     * @see com.sun.org.apache.xpath.internal.objects.XNumber
     * @see com.sun.org.apache.xpath.internal.objects.XString
     * @see com.sun.org.apache.xpath.internal.objects.XRTreeFrag
     */
    public static XObject eval(Node contextNode, String str)
            throws TransformerException {
        return eval(contextNode, str, contextNode);
    }

    /**
     * Evaluate XPath string to an XObject.
     * XPath namespace prefixes are resolved from the namespaceNode.
     * The implementation of this is a little slow, since it creates
     * a number of objects each time it is called.  This could be optimized
     * to keep the same objects around, but then thread-safety issues would arise.
     *
     * @param contextNode   The node to start searching from.
     * @param str           A valid XPath string.
     * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces.
     * @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
     * @throws TransformerException
     * @see com.sun.org.apache.xpath.internal.objects.XObject
     * @see com.sun.org.apache.xpath.internal.objects.XNull
     * @see com.sun.org.apache.xpath.internal.objects.XBoolean
     * @see com.sun.org.apache.xpath.internal.objects.XNumber
     * @see com.sun.org.apache.xpath.internal.objects.XString
     * @see com.sun.org.apache.xpath.internal.objects.XRTreeFrag
     */
    public static XObject eval(Node contextNode, String str, Node namespaceNode)
            throws TransformerException {

        // Since we don't have a XML Parser involved here, install some default support
        // for things like namespaces, etc.
        // (Changed from: XPathContext xpathSupport = new XPathContext();
        //    because XPathContext is weak in a number of areas... perhaps
        //    XPathContext should be done away with.)
        XPathContext xpathSupport = new XPathContext(JdkXmlUtils.OVERRIDE_PARSER_DEFAULT);

        // Create an object to resolve namespace prefixes.
        // XPath namespaces are resolved from the input context node's document element
        // if it is a root node, or else the current context node (for lack of a better
        // resolution space, given the simplicity of this sample code).
        PrefixResolverDefault prefixResolver = new PrefixResolverDefault(
                (namespaceNode.getNodeType() == Node.DOCUMENT_NODE)
                        ? ((Document) namespaceNode).getDocumentElement() : namespaceNode);

        // Create the XPath object.
        XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null);

        // Execute the XPath, and have it return the result
        // return xpath.execute(xpathSupport, contextNode, prefixResolver);
        int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);

        return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
    }

    /**
     * Evaluate XPath string to an XObject.
     * XPath namespace prefixes are resolved from the namespaceNode.
     * The implementation of this is a little slow, since it creates
     * a number of objects each time it is called.  This could be optimized
     * to keep the same objects around, but then thread-safety issues would arise.
     *
     * @param contextNode    The node to start searching from.
     * @param str            A valid XPath string.
     * @param prefixResolver Will be called if the parser encounters namespace
     *                       prefixes, to resolve the prefixes to URLs.
     * @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null.
     * @throws TransformerException
     * @see com.sun.org.apache.xpath.internal.objects.XObject
     * @see com.sun.org.apache.xpath.internal.objects.XNull
     * @see com.sun.org.apache.xpath.internal.objects.XBoolean
     * @see com.sun.org.apache.xpath.internal.objects.XNumber
     * @see com.sun.org.apache.xpath.internal.objects.XString
     * @see com.sun.org.apache.xpath.internal.objects.XRTreeFrag
     */
    public static XObject eval(
            Node contextNode, String str, PrefixResolver prefixResolver)
            throws TransformerException {

        // Since we don't have a XML Parser involved here, install some default support
        // for things like namespaces, etc.
        // (Changed from: XPathContext xpathSupport = new XPathContext();
        //    because XPathContext is weak in a number of areas... perhaps
        //    XPathContext should be done away with.)
        // Create the XPath object.
        XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null);

        // Execute the XPath, and have it return the result
        XPathContext xpathSupport = new XPathContext(JdkXmlUtils.OVERRIDE_PARSER_DEFAULT);
        int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode);

        return xpath.execute(xpathSupport, ctxtNode, prefixResolver);
    }
}
